This is 

Trichocereus knuthianus !

I personally sourced this cultivar years ago from the Ed Gay collection! Same grower that SS originally received their knuthianthus and named it  SS03 from . I’ve pictured the original book of Ed gay who sourced this exact cultivar in 1962 .I received this directly from Dons garden , who received it from directly Eds garden.  I’m making sure to keep it under the same name as ss calls it to make sure there isn’t any confusion ! 

beautiful notchy specimen with a clean cut callous ready to ship , you will receive this exact pictured cactus !! Not often seen or offered ! Grab this now , it will go fast and I don’t have a bunch ! This is a small cutting that will easily root , great way to get ahold of these genitics .
All sides are pictured, ruler is in inches and soda can is for size reference